Previous hydraulic tools I have developed are provided with self-contained pumps to provide the necessary pressurized fluid. Such pumps may be hand operated, as in the Hydraulic Riveter shown in my U.S. Pat. No. 4,263,801 granted Apr. 28, 1981, or they may be motor driven, as in the Hydraulic Log Splitter of my U.S. Pat. No. 4,498,293 dated Feb. 12, 1985. In operation of such tools, a pump plunger is retracted to draw hydraulic fluid radially inward from a surrounding reservoir and through a spring-biased, highly finished ball check valve into a pump chamber. Then, when the pump rod is extended, the fluid is projected into a pressure chamber within a cylinder. While such tools have been extremely effective, they can be made even more compact and at less cost if the inlet ball check valves could be replaced by simpler devices.